PEEK’s superior material properties make it a fit for many areas of medicine, including spinal fusion, dentistry, trauma fixation and cardiovascular medicine, among other fields. This high-performance polymer has been used in medicine for over 20 years, and there are still exciting developments to come for PEEK medical devices.
In the present, there are many medical devices where PEEK serves as a frontline material choice, including:
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Interbody fusion cages –
Interbody fusion cages are used in spinal fusion applications to provide additional stability thereby helping to relieve pain. Spinal fusion is indicated in patients suffering from degenerative disc disease, spondylolisthesis, spinal stenosis, or damage due to fractures or tumors.
During spinal fusion, the problematic disc is removed from the body and replaced with a bone graft and interbody fusion cage. The cage provides an ideal environment for the bone graft to fuse the two vertebrae together, ensuring predictable, stable growth. The fusion cage becomes a permanent part of the spine, so it must be manufactured from biocompatible materials.
PEEK provides that total biocompatibility and offers several more advantages. For example, PEEK’s flexural modulus is similar to cortical bone, so it shares weight and handles force like bone. This makes PEEK an ideal bone replacement material, because it will not bear too much weight and cause subsidence. Subsidence is a noted issue with titanium implants for this reason, and PEEK’s subsidence rates are much lower, according to multiple research studies.
PEEK’s pure radiolucency is also useful in spinal fusion applications, as it allows surgical teams to assess the patient without the implant interfering with medical imaging. This includes CT, MRI and X-ray scans, so PEEK can be used with a variety of imaging technologies.
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Dentistry –
PEEK is a frontline choice for some dental applications, including dental implants and removable partial dentures. PEEK’s biocompatibility means it can be implanted in the jaw or used in the oral cavity without causing issues.
The rise of CAD/CAM dentistry has been especially beneficial for PEEK, as CAD/CAM dentistry takes precise 3D models of a patient’s mouth and machines a device that fits that patient perfectly. As PEEK tolerates machining extremely well, it is a good fit for a CAD/CAM approach.
PEEK partial dentures are prized for their excellent aesthetics and comfort. Aesthetically, PEEK can be color matched to surrounding tissues, which is something that can’t be done with other dental materials. This means PEEK devices are inconspicuous, even when the patient’s mouth is open. PEEK partial dentures are also comfortable, as they are lightweight and shaped to fit the patient precisely. Also, PEEK does not alter the patient’s taste and does not irritate tissues, so it doesn’t interfere with the patient’s ability to eat or talk.
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Cardiovascular devices –
PEEK is also a top choice for several cardiovascular devices, including medical tubing. PEEK tubing can be used to deliver cardiovascular devices like replacement valves and stents. It is also incorporated into defibrillators and ablation catheters.
What makes PEEK an ideal tubing material is its low coefficient of friction and flexibility. Together, these properties make PEEK well-suited for the cardiovascular network, and the polymer offers strong pushability and navigation. Pushability refers to the amount of force required to advance the tubing to the treatment site, while navigation refers to how well the material can move through nonlinear segments of the cardiovascular network. These two traits are usually at odds, because improving one usually adversely affects the other. Fortunately, PEEK tubing provides an optimal mix of both, so it can be used in most locations of the vascular network.
PEEK’s electrical properties also make it a good fit for ablation catheters, defibrillators and any device that works by delivering precise electrical discharges. PEEK can help control these discharges, reducing risk of electrocution and burn injuries to the patient.
The polymer is also relied on in some emerging cardiovascular procedures. One of these is the Less Invasive Ventricular Enhancement (LIVE) procedure, which is indicated in patients who have suffered heart damage, usually caused by a heart attack. During the LIVE procedure, a pair of anchors are positioned over the scar tissue and held together by a PEEK tether. The anchors move scar tissue out of the way in order to restore ventricular function, and the tether keeps the anchors properly aligned. The LIVE procedure is a safer alternative to previous forms of ventricular enhancement, which required several incisions to the heart.
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Trauma fixation –
Among biomaterials, PEEK possesses elite mechanical properties, making it a strong choice for bone plates and screw systems. PEEK’s cortical bone-like modulus, resiliency and pull-out strength are particularly important for trauma fixation applications. In short, PEEK can handle the compressive and tension forces applied to trauma fixation devices, resist failure and prevent subsidence with appropriate load-sharing abilities.
Many medical devices are made from PEEK, and some of these devices, like interbody fusion cages, are being improved upon constantly. New fusion cages, for example, are being developed with materials that attract bone growth, like hydroxyapatite and zeolite.
With its existing, impressive capabilities and future potential, PEEK has established itself as a critical biomaterial, and one that will only become more essential with time.
FAQ
Why are PEEK implants replacing titanium implants?
PEEK implants have a flexural modulus that’s similar to cortical bone, so they are less likely to cause stress shielding, and by extension, subsidence. Subsidence refers to settling, or caving in, of bone. Titanium implants are more likely to cause subsidence because titanium bears weight instead of sharing it.
What additives can be mixed with PEEK medical devices?
PEEK can be augmented with chopped carbon fibers (CFR PEEK), and this provides additional strength and stiffness to the polymer. Barium sulfate can also be added to PEEK to make it more radiopaque for applications where it would be helpful to see the implant on medical imaging.
What makes PEEK a good choice for cardiovascular tubing?
PEEK can be converted into extremely small cross sections and is a low-friction material. This makes it an ideal choice for the cardiovascular network, which is nonlinear in design. PEEK tubing offers excellent pushability and navigation, so it can be steered through vascular branches with little difficulty.